Conventional monitor hinge mechanisms allowing a monitor mounted on a ceiling of a motor vehicle, e.g., to open and close are arranged to have a support structure where a fulcrum shaft for opening and closing the monitor is fixed in position and the monitor having the shape of a rectangular plate rotates about that fixed support. Such a support structure can condition the monitor to be closed along a mounting surface such as a ceiling in the accommodated state, and further, can condition the monitor to be opened up to a nearly vertical position with respect to the mounting surface such that the monitor can be easily seen by a viewer when used. However, the support structure using such a fixed support occupies a space equivalent to the approximately maximum external shape of the monitor on the side remote from the fixed support in the monitor-opened position. Consequently, the amount of projection of the monitor projecting from the ceiling is large in the case of an in-vehicle monitor suspended from a ceiling, which results in the possibility of obstructing a driver's rearward visibility through a room mirror. Upsizing of a monitor in recent years strengthens that tendency.
Meanwhile, there is a hinge apparatus including two hinges as a means for turning a cover panel of a hand-held computer pocketbook (see Patent Document 1, for instance). In that hinge apparatus, a first hinge acts from the state where the cover panel is closed to the state of a certain panel-opened angle, and a second hinge begins working when the opening angle of the panel exceeded that panel-opened angle. The hinge apparatus has a hinge mechanism where the first hinge operates by a first torque over a certain range, and after exceeding the range, the hinge becomes unable to operate because of being blocked by a restriction force; however, when a second torque larger than the first torque but insufficient to overcome that restriction force is applied, the second hinge operates to cause the cover panel to turn over the range of a second movement.
However, that hinge mechanism controls the switch from the first hinge to the second hinge by the rotating torque, which may cause the second hinge to rotate before the first hinge rotates when force is applied in the direction of shaft axis of a first shaft where the first hinge does not easily rotate, and results in the possibility of breakage of a lock pawl for the cover panel. Further, the cover panel exhibits a rotation mechanism where the panel reverses in such a manner as to surround a bottom panel on the first hinge and the second hinge when rotated, which requires a sufficient thickness for the space where the mechanism moves. This makes the hinge mechanism unsuitable for downsizing the space needed for rotation.
Patent Document 1: JP-A-1997-130058
In a conventional monitor opening and closing mechanism, when a monitor mounted on a ceiling of a motor vehicle is opened to a predetermined position and is seen and listened to by an occupant, a driver's view is obstructed because the monitor projects in a direction where the driver's rearward visibility through a room mirror is obstructed, in an amount remaining as determined by the radius of rotation from the fixed support. Moreover, it is also impossible to say that the hinge mechanism disclosed in Patent Document 1 is suitable for supporting an in-vehicle monitor, as described above. Those mechanisms each have a problem to be solved.
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an improved monitor opening and closing mechanism that does not restrict a driver's rearward visibility through a room mirror.